The invention concerns a method of continuously tempering a fat-containing, chocolate-like mass, whereby the mass is subjected to a primary cooling, a subsequent secondary cooling creating crystals in the mass, and a final reheating.
The invention further concerns an apparatus for continuous tempering of a fat-containing, chocolate-like mass, comprising a primary cooling section, a subsequent secondary cooling section in which crystals are created in the mass, and a final reheating section.
For many years, the method has been used extensively for production of a great variety of chocolate-like masses. Before tempering, the chocolate-like mass is warmed up to around 40-60.degree. C. After tempering, the mass typically has a temperature of around 29-33.degree. C., whereafter it is being used for many purposes, such as being filled in moulds, deposited on top of other articles, etc.
The aim of the tempering process is briefly spoken, to create a mass with a portion and a type of crystals, that satisfies, that the chocolate-like mass for sure will solidify to a state, which results in a "high" quality article. To the skilled person, a "high quality" article brings along a glossy surface, long time storage capacity without diffusion of fat content to the surface, crispy break, and of course good taste as well. Experience has gained the knowledge to the skilled person, that such high quality is heavily dependent upon the type of crystals created in the mass during tempering, as well as the actual portion of such crystals, either in relation to the weight of the total mass, or in relation to the fat content of the mass.
Extensive scientific research has since long provided the teaching, that of the several available crystal forms, which may be performed during tempering of a chocolate-like mass, it is the stable .beta.-crystals only, which for sure provides high quality chocolate-like mass.
Prior Art
In view of this, methods and apparatuses by which the primary cooling is performed in a first section, and crystals are performed in a secondary cooling section has been available for many years. The theory is, that the mass is to be cooled down in the first section to a temperature "close" to the temperature, at which stable crystals perform in the mass. It is well known, that for each type of chocolate-like mass, whatever its composition may be, such temperature may be determined by simple tests. For most types of chocolate-like mass, such temperatures are between 26.degree. C. and 30.degree. C. Thereafter, the mass is caused to pass through the secondary cooling section, in which the crystals are created. By observing, that the temperature of the cooling medium is sufficiently low in that section, the heat caused by the crystal formation is removed entirely. The mass temperature could be constant or lowered slightly further in the secondary section. Thereby, the skilled person was at least sure, that crystals were performed in that secondary section.
Such apparatuses are among the latest teachings known from EP 0 472 886 A1 and EP 0 685 168 A1. By these known apparatuses the cooling sections and the reheating section is arranged on top of each other in a column, each of which cooling sections comprise at least one mass chamber through which the mass flows, as well as at least one medium chamber through which the cooling medium flows. The mass is subjected to stirring means arranged in the mass chambers.
By these teachings various types of cooling medium circuits are suggested for the secondary section. Common to each suggestion is that the circuit is laid out to achieve an independent control of the cooling for the secondary cooling stage only. Thereby the formation of stable crystals in the secondary section only, may be controlled quite accurately.
However, practice as well as scientific testing has shown, that the temperature of the cooling water flowing through the primary cooling section differs so much as 10.degree. C. for the apparatus type disclosed in EP 0 472 886 A1 when the temperature or flow of the mass through the apparatus changes. The unavoidable effect measured was, that the temperatures of the cooling surfaces in that primary cooling section fluctuated extensively as well. It was surprisingly realised that this was the cause to a varying amount of crystals in the ready tempered mass.
By further testing it was obtained, that by this apparatus type it was impossible to perform a control, so that creation of crystals were limited to the secondary cooling section only, as it supposedly was the intention. Though minor temperature fluctuations were experienced by the apparatus type of EP 0 685 168 A1 it was not possible with this apparatus type either to obtain a desired, essentially constant portion of crystals in the tempered mass when mass temperature or flow changes. By constant portion of crystals is meant, that the amount of crystals constitutes a constant percentage of the total amount of the tempered mass.
The conclusion was that by none of the above-referred teachings a constant portion of crystals could be obtained in the tempered mass. This is due to the fact, that the cooling of the primary cooling section of these known apparatuses is controlled in response to the temperature of the mass only. Thereby it is unavoidable, that the temperature of the cooling surfaces of the mass chambers in the primary cooling section changes when the temperature or the flow of the mass changes. When the temperature of the surfaces fluctuates downwards the unintended effect is, that the crystal formation area of the secondary cooling section is extended by areas of the primary cooling section, in which the cooling water temperature from time to time is sufficiently low for crystals to be performed in the mass. The end result is a varying as well as a higher portion of crystals in the mass from time to time than intended, which is not desirable.
The skilled person always tries to reach a tempered mass with a portion of stable crystals, which is kept as constant as possible during the total production. When the exact, and therefore desired amount of crystals for the specific chocolate type has been established empirically, the aim is to reach that desired amount as closely as possible for every article produced. Only then, the manufacturer is sure, that the good qualities such as a glossy surface, long time storage capacity without diffusion of fat content to the surface, crispy break, and of course good taste is preserved for every article produced.
As it is the actual control performed for the cooling sections during tempering of the mass that determines the achieved portion of crystals in every article produced, it is of outmost importance to establish such control as exact and reliable as possible with a view of obtaining a constant a portion of crystals in the mass.
Furthermore, the EP 0 472 886 A1 teaches, that a "high" portion of stable crystals in the tempered mass is desirable. The teaching EP 0 289 849 A1 further states, that 4-5% stable crystals of the mass should be reached during tempering. The desire for such a "high" content of stable crystals actually verifies a long time impression within the field of tempering.
However, for the latest few years the desire for a "high" content of stable crystals has suddenly been left. The persons skilled within the field have recognised, that scientific research today guides in the opposite direction, and that is for a very "low" portion of stable crystals in the mass. Such "low" portion is preferably around 0.2-2.0% of the fat content of the mass. It is evident, that when aiming at such "low" portions of crystals to be kept constant, it is even more important to minimise the variations in crystal amount in relation to the desired "low" portion, as every actual variation gives a much greater percentage deviation from the desired portion than compared to, when a "high" portion of crystals is aimed at.
Therefore, the general change within the field towards such comparably "low" portions of stable crystals makes it even more important to achieve an exact control of the cooling. Only with an exact and reliable control of the cooling, an essentially constant portion of crystals in the mass may be achieved, especially whatever the variations in the mass temperature or flow may be.